Contents

1 Etiology and pathophysiology

Primary hyperparathyroidism results from a dysfunction in the parathyroid glands themselves, with oversecretion of PTH. The calcium controlling feedback control system is disconnected at the site of parathyroid glands. It is usually caused by parathyroid adenomas that lose their sensitivity to circulating calcium levels that normally would inhibit PTH secretion. Here, usually, only one of the four parathyroid glands is affected. A less common cause is multiple endocrine neoplasia (MEN) where usually all four glands are affected.

Tertiary, quartary and quintary hyperparathyroidism are rare forms that are caused by long lasting disorders of the calcium feedback control system.

2 Signs and symptoms

In most cases, hyperparathyroidism is diagnosed incidentally as the majority of patients with hyperparathyroidism are asymptomatic. Manifestations of hyperparathyroidism usually involve the kidney (renal calculi) and the skeletal system (reduced bone density due to replacement of calcified tissue by fibrous tissue, termed osteitis fibrosa cystica or Morbus Recklinghausen)

3 Diagnosis

The gold standard of diagnosis is the PTH immunoassay. Once an elevated PTH has been confirmed, goal of diagnosis is to determine whether the hyperparathyroidism is primary or secondary in origin by obtaining a serum calcium level. If the calcium level is high, then the diagnosis is very likely primary hyperparathyroidism; if low or normal, then it is most likely secondary hyperparathyroidism. The differentiation to tertiary, quartary or quintary hyperparathyroidism requires additional consideration of the patient's history.

4 Therapy

Therapy is initially directed at hypercalcemia, if symptomatic (see hypercalcemia). If asymptomatic, treatment should subsequently be directed towards the underlying cause, which includes surgical removing of affected parathyroid glands in cases of primary, tertiary or quintary hyperparathyroidism, or treating underlying illness in secondary or quartary hyperparathyroidism.